The present invention relates generally to systems for providing sand to locomotives for improving traction and stopping performance on steel rails, and more specifically to an improved sand delivery system, incorporating a pressurized sand distribution chamber.
Conventional locomotives have internal, pneumatically pressurized sand delivery systems used to blow sand onto the rails in advance of the traction wheels. These systems periodically need refilling. Locomotive sand refilling systems are known in the art, and have been provided in various configurations. Historically, sand was delivered to the locomotives by elevated gravity tanks with downspouts. In other systems, an operator rides in a cab elevated above the track on a rolling gantry system. The operator manually controls a nozzle from a central hopper to deliver sand into a designated compartment in the locomotive. The industry gradually adopted systems that provide sand under pressure. In a typical pneumatic system, sanding stations are positioned along the track and receive sand from a central hopper. Each tower has at least one distribution hose that operators manipulate to align with the locomotive intake. Sand is then propelled pneumatically directly into the locomotive hopper
A common problem with traditional gravity locomotive sanding systems is a relatively large infrastructure cost in gantries, towers, and related accessories. However, in such systems it is still difficult to properly align the locomotive under the sand distribution point. A drawback of the newer, pneumatic conventional locomotive sand delivery systems is that operators often have to manually position the sand delivery hose in the locomotive intake, and the heavy, unwieldy hose is difficult to maneuver. Unwanted sand spills can result. Still another problem of conventional locomotive sanding systems is the significant amount of dust that is generated during the filling process.
Yet another drawback of conventional sand refilling systems is that they include sensors for determining when the locomotive is full, to prevent sand from over-feeding. This sensing system adds complexity, and can fail. Also, the sensing system requires that a probe stick be inserted into the locomotive sandbox, which is often guarded with a screen. The hose must also be “purged” by blowing it clear to reduce its weight before removal by an operator. Finally, the motive air used to propel the sand creates some dust, which can be a safety issue due to the danger of silicosis for operators.